[Sc©[3]CPP]⁺: A Viable Metal-Centered [3]Cycloparaphenylene

Area of Science:

• Organic Chemistry
• Computational Chemistry
• Materials Science

Background:

• Cycloparaphenylenes ([n]CPPs) are strained cyclic aromatic molecules.
• The smallest [3]Cycloparaphenylene ([3]CPP) isomer is unstable due to high strain, readily converting to a bond-shift (BS) isomer.
• Achieving stable [3]CPP is crucial for developing novel carbon-based materials.

Purpose of the Study:

• To computationally investigate the stabilization of [3]Cycloparaphenylene ([3]CPP) through guest atom encapsulation.
• To explore the potential of metal atom hosting for overcoming inherent molecular strain in [n]CPPs.
• To assess the thermodynamic and dynamic stability of a metal-encapsulated [3]CPP complex.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model the electronic structure and energetics.
• Binding energy calculations quantified the interaction between the guest atom and [3]CPP.
• Molecular dynamics simulations were performed to evaluate thermal stability.

Main Results:

• Scandium (Sc) was found to effectively stabilize [3]CPP by forming a [Sc©[3]CPP]+ complex.
• Strong π-Sc donation-backdonation interactions were identified as the key stabilization mechanism.
• The calculated binding energy (-205.7 kcal/mol) significantly offsets the strain energy (170.3 kcal/mol) and the [3]CPP to [3]BS energy difference (44.2 kcal/mol).
• Dynamic simulations indicated stability of the [Sc©[3]CPP]+ complex up to 1500 K.

Conclusions:

• Encapsulating a Scandium atom is a viable strategy to stabilize the highly strained [3]Cycloparaphenylene ([3]CPP).
• The [Sc©[3]CPP]+ complex exhibits significant thermodynamic and thermal stability, suggesting feasibility for experimental synthesis.
• This approach offers a pathway to access previously inaccessible strained molecular architectures for advanced materials.